Complete the boundary-mirror removal begun with the step mirrors: drop `agent/turn-start` and `agent/turn-end` from the agent event taxonomy. Turn and step boundaries are now read exclusively off the durable `session/event` feed (`turn/start`/`turn/end`/`step/start`/`step/end`) — there is no `agent/*` mirror for any boundary. - loop.ts: delete both turn emits; `closeTurn` loses its `emit` parameter and its now-unreachable idempotency guard (it is called exactly once per turn, on mutually exclusive normal/catch paths); `failTurn` loses the dead post-close branch that only a throwing turn-end LISTENER could reach. - ui-stdio: render turn boundaries from `session/event`, recovering the short agent label from an `agent/created`→id map (the `turn/start` event carries only the turn number, and the session id is not reliably the agent id). ui-stdio is a disposable test REPL, so this migration retires the sole justification the event-domain-semantics RFC gave for KEEPING the turn mirrors. - Tests: reason/turn-number collectors and the boundary-ordering test now read `session/event`; the throwing-turn-boundary-LISTENER tests are deleted (that code path no longer exists). A new test covers the outer-catch disposed branch via a pre-step listener that disposes-then-throws (the surviving real path). - Docs: promote the "remove agent boundary mirror events" RFC to implemented (amended/narrowed — `agent/steering` is RETAINED, not a boundary mirror); update the event-domain-semantics + turn-enclosure RFCs, architecture.md, the cookbook, the ACP/agent/ui-stdio prose, and regenerate the cordis catalog. `agent/steering` and `agent/stream-chunk` are explicitly out of scope (not durable-boundary mirrors). ACP is unaffected — it already settles from the log's `turn/end` + `agent/status`; snapshot goldens are byte-unchanged.
support/ — dev/test/example infrastructure
Packages that exist to serve development, testing, and the examples rather than to ship as product API. They are real workspace packages (typed, tested, under the coverage gate), but they carry lower compatibility expectations: they may change or be removed when the development need behind them does, without the deprecation care a product package would warrant.
| Package | Role | ctx key |
|---|---|---|
invariants/ |
Dev-mode event-contract invariants + session-log freeze | (listens on session/*, agent/*) |
ui-stdio/ |
Minimal stdio (readline) UI plugin: renders agent/* events, feeds stdin lines to the agent |
(drives ctx.agents) |
llm-replay/ |
Record/replay adapter: short-circuits llm/stream from a recorded session JSONL (keyless snapshot tests) |
(listens on llm/stream) |
subagent-mock/ |
Scripted SubagentProvider for deterministic seam/tool tests |
(registers on ctx.subagents) |
invariants runs only in dev mode (contract checks, not runtime behavior). ui-stdio and llm-replay were extracted from the examples for reuse and to bring them under the per-file coverage gate; they back the demos and the snapshot test tier. subagent-mock exercises the real ctx.subagents load path without a model or child agent. A package graduates OUT of support/ into a product group only when it gains documented product consumers.